National Demonstration Center for Experimental Chemistry Education, Hunan Engineering Laboratory for Analyse and Drugs Development of Ethnomedicine in Wuling Mountains, Jishou University, Jishou 416000, China.
State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093, China.
Med Chem. 2021;17(9):1046-1059. doi: 10.2174/1573406416999200818152440.
Thiourea is a classical urease inhibitor which is usually used as a positive control, and many N,N'-disubstituted thioureas have been determined as urease inhibitors. However, due to steric hindrance, N,N'-disubstituted thiourea motif could not bind urease as thiourea. On the contrary, N-monosubstituted thiourea with a tiny thiourea motif could theoretically bind into the active pocket as thiourea.
A series of N-monosubstituted aroylthioureas were designed and synthesized for evaluation as urease inhibitors.
Urease inhibition was determined by the indophenol method and IC values were calculated using computerized linear regression analysis of quantal log dose-probit functions. The kinetic parameters were estimated via surface plasmon resonance (SPR) and by nonlinear regression analysis based on the mixed type inhibition model derived from Michaelis-Menten kinetics.
Compounds b2, b11, and b19 reversibly inhibited urease with a mixed mechanism, and showed excellent potency against both cell-free urease and urease in the intact cell, with IC values being 90- to 450-fold and 5- to 50-fold lower than the positive control acetohydroxamic acid, respectively. The most potent compound b11 showed an IC value of 0.060 ± 0.004μM against cell-free urease, which bound to urea binding site with a very low KD value (0.420±0.003nM) and a very long residence time (6.7 min). Compound b11 was also demonstrated to have very low cytotoxicity to mammalian cells.
The results revealed that N-monosubstituted aroylthioureas bound to the active site of urease as expected, and represent a new class of urease inhibitors for the development of potential therapeutics against infections caused by urease-containing pathogens.
硫脲是一种经典的脲酶抑制剂，通常用作阳性对照，许多 N,N'-二取代硫脲已被确定为脲酶抑制剂。然而，由于空间位阻，N,N'-二取代硫脲结构不能像硫脲一样结合脲酶。相反，具有微小硫脲结构的 N-单取代硫脲理论上可以作为硫脲结合到活性口袋中。
设计并合成了一系列 N-单取代芳酰基硫脲，以评估其作为脲酶抑制剂的活性。
采用吲哚酚法测定脲酶抑制活性，并用计算机线性回归分析量子对数剂量-概率函数计算 IC 值。通过表面等离子体共振（SPR）和基于米氏动力学推导的混合抑制模型的非线性回归分析来估算动力学参数。
化合物 b2、b11 和 b19 以混合机制可逆地抑制脲酶，对无细胞脲酶和完整细胞中的脲酶均表现出优异的活性，IC 值分别比阳性对照乙酰氧肟酸低 90 至 450 倍和 5 至 50 倍。最有效的化合物 b11 对无细胞脲酶的 IC 值为 0.060±0.004μM，它与尿素结合位点具有非常低的 KD 值（0.420±0.003nM）和非常长的停留时间（6.7 min）。化合物 b11 对哺乳动物细胞也表现出非常低的细胞毒性。
结果表明，N-单取代芳酰基硫脲如预期的那样结合到脲酶的活性位点，代表了一类新的脲酶抑制剂，可用于开发针对含脲酶病原体感染的潜在治疗药物。
